1. Field of the Invention
The invention discloses the use of novel salicylate esters of silicone compounds which an ester linkage, and a silicone polymer. Compounds of the invention are made by reacting (a) a carboxy silicone, and (b) salicylic acid to form an ester. Compounds of the invention by virtue of (i) the silicone group, (ii) the ester group and (iii) the compounds are applied to the skin as ultra violet absorbing group salicylic group, the compounds are effective durable ultra-violet absorbers.
The reaction used to prepare the compounds of the present invention is an esterification of a carboxy silicone and salicylic acid. The resulting ester provides ultra violet absorbance and is durable to substrates like textile fabrics, hair and skin.
2. Arts and Practices
Silicone compounds have been known to be active at the surface of plastic, cellulosic and synthetic fibers as well as paper. They are good nondurable lubricants and are very stable to oxidation, however, their high cost and lack of efficiency at low concentrations as well as low durability have made their acceptance in commercial products quite low. In all instances, commercially available quaternaries are the active ingredient in traditional laundry care markets, with little or no silicone added.
The low efficiency and low durability of dimethyl-polysiloxane is due to the fact that it is very water insoluble and deposits on the surface to obtain a minimum free energy in the solution. Simply, the silicone oil delivery to the surface by hydrophobic binding, not chemical bonding. At the surface, the dimethylpolysiloxane is a very effective fiber lubricant, however, there are two drawbacks, first; the dimethylpolysiloxane is not chemically bonded so the effect is very transient and disappears with one washing, and second; since there is no reaction of the dimethylpolysiloxane to the surface an equilibrium between fiber absorbed dimethylpolysiloxane and dimethylpolysiloxane in the dispersion results in very inefficient percentage of silicone deposited. A large amount of the expensive silicone goes down the drain with the waste water.
Silicone oils do not provide ultra violet absorption, and consequently protection from the damaging effects of the sun. The aromatic compounds that provide this type of absorbance are not durable to the surfaces of substrates.
U.S. Pat. No. 3,511,699 to Sterman issued May 12, 1970 teaches that epoxy compounds placed in the silicone backbone by hydrosilation can be cured onto certain fibers to give improved substantivity. The substantivity is based upon the reaction of hydroxyl groups on the cellulosic and the epoxy group in the silicone polymer. The resulting bond is a ether linkage and a new hydroxyl group. While a definite improvement over other compounds the efficiency and durability of the were not good enough to allow for cost effective incorporation of these materials in detergent formulations.